Human milk is generally the food of choice for preterm and full term infants because of its nutritional composition and immunologic benefits. The source of human milk can be, e.g., a donor or the infant's mother. The nutritional value of raw or conventionally-processed donor milk, however, varies and, in most instances, is not sufficient to meet the needs of preterm infants. In addition, a possibility of bacterial, viral and other contamination of raw donor milk exists. Even the mother's own milk is often not nutritionally sufficient for the premature infant. It is often desirable to feed preterm infants milk that is fortified with various supplements, e.g., oligosaccharides. Compositions that contain human milk oligosaccharides can also be useful as supplements for infants, children, and adults who have or are at risk of developing various disorders and diseases, e.g., infections or immune deficiencies, and who need to develop and/or maintain proper gut flora.